Endace DAG 7.1S, Руководство пользователя

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EDM 01-17 DAG 7.1S Card User Guide
Chapter 5:
Synchronizing Clock Time
Overview
The Endace DAG cards have sophisticated time synchronisation capabilities,
which allow for high quality timestamps, optionally synchronized to an
external time standard.
The core of the DAG synchronisation capability is known as the DAG
Universal Clock Kit (DUCK).
An independent clock in each DAG card runs from the PC clock. The card’s
clock is initialised using the PC clock, and then free-runs using a crystal
oscillator.
Each card's clock can vary relative to a PC clock, or other DAG cards.
DUCK
Configuration
The DUCK is designed to reduce time variance between sets of DAG cards or
between DAG cards and coordinated universal time [UTC].
You can obtain an accurate time reference by connecting an external clock to
the DAG card using the time synchronisation connector. Alternatively you
can use the host PCs clock in software as a reference source without any
additional hardware.
Each DAG card can also output a clock signal for use by other cards.
Common
Synchronization The DAG card time synchronisation connector supports a Pulse-Per-Second
(PPS) input signal, using RS-422 signalling levels.
Common synchronisation sources include GPS or CDMA (cellular telephone)
time receivers.
Endace also provides the TDS 2 Time Distribution Server modules and the
TDS 6 units that enable you to connect multiple DAG cards to a single GPS
or CDMA unit.
For more information please refer to the Endace website at
http://www.endace.com/accessories.htm , or the TDS 2/TDS 6 Units
Installation Manual .
©2006 31 Version 2: May 2006